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• Nov

  13

  Appl Math: Nick Moore on "Reversals of the Large-scale Circulation in Thermal Convection"

  McCormick-Engineering Sciences and Applied Mathematics (ESAM)

  11:15 AM M416, Technological Institute

  EVENT DETAILS

  Title: Reversals of the Large-scale Circulation in Thermal Convection

  Speaker: Nick Moore, Colgate University

  Abstract: Thermal convection, or the tendency of heat to rise and cool material to descend, often gives rise to a large-scale circulatory flow structure. It is known that the large-scale circulation (LSC) can undergo spontaneous reversals. In the atmosphere, reversals can result in a sudden change in wind direction, while in Earth’s liquid core, reversals may play a role in magnetic dipole shifts. I will discuss LSC reversals in the context of 2D annular thermal convection. Through comparison with direct numerical simulations, I’ll show that a low-dimensional dynamical system derived systematically from Galerkin truncation of the governing equations accurately describes a sequence of parameter bifurcations, including the onset of circulatory flow, the appearance of chaotic LSC reversals, and finally a high-Rayleigh-number state of periodic LSC reversals with small-scale turbulence. When cast in terms of the fluid’s angular momentum and center of mass, the model reveals equivalence to a pendulum system with driving term that raises the center of mass above the fulcrum. It is the competition between driving, restoring, and damping that leads to the range of convective states. This physical picture yields accurate predictions for the frequency of regular LSC reversals in the high Rayleigh-number limit and offers a transparent mechanism for reversals. I will briefly discuss extensions of the model, including one that accurately recovers the gross heat transport.

  Zoom: https://northwestern.zoom.us/j/98171601500

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  TIME Thursday, November 13, 2025 at 11:15 AM - 12:15 PM

  LOCATION M416, Technological Institute    map it

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  CONTACT Ted Shaeffer    ted.shaeffer@northwestern.edu EMAIL

  CALENDAR McCormick-Engineering Sciences and Applied Mathematics (ESAM)

• Nov

  20

  Appl Math: Ed Lyman on "Elastic and Dynamic Response of Membranes Across Scales"

  McCormick-Engineering Sciences and Applied Mathematics (ESAM)

  11:15 AM M416, Technological Institute

  EVENT DETAILS

  Title: Elastic and Dynamic Response of Membranes Across Scales

  Speaker: Ed Lyman, University of Delaware

  Abstract: Cell membranes are quasi-2D soft materials, about 5 nm thick but with hundreds of square microns of surface area. They are a bilayer structure, assembled from amphiphilic molecules (lipids) and proteins. The function of membranes imposes challenging design constraints: impermeable yet fluid, mechanically robust yet deformable. Across the tree of life, cells meet these challenges by synthesizing a diverse array of lipids, whose chemistry and interactions determine the key continuum properties, like stiffness against bending and the viscosity which controls diffusion and encounter of membrane bound signaling partners. In this talk I will present our group's work using simulations to connect lipid chemistry and membrane properties, focusing on two applications. The first project considers the membranes of a family of marine invertebrates called ctenophores, which synthesize a specialized lipid chemistry to maintain membrane deformability at high pressure. The second project focuses on how lipid chemistry is used to control the viscosity of the membrane, and the challenges that come with trying to measure the viscosity of soft, thin, not-quite two dimensional fluids.

  Zoom: https://northwestern.zoom.us/j/95131921396

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  To subscribe to the Applied Mathematics Colloquia List send a message to LISTSERV@LISTSERV.IT.NORTHWESTERN.EDU with the command:

  SUBSCRIBE esam-seminar FirstName LastName

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  TIME Thursday, November 20, 2025 at 11:15 AM - 12:15 PM

  LOCATION M416, Technological Institute    map it

  ADD TO CALENDAR

  CONTACT Ted Shaeffer    ted.shaeffer@northwestern.edu EMAIL

  CALENDAR McCormick-Engineering Sciences and Applied Mathematics (ESAM)

• Dec

  13

  Northwestern Engineering PhD Hooding and Master's Recognition Ceremony

  McCormick School of Engineering and Applied Science

  4:00 PM Pick-Staiger Concert Hall

  EVENT DETAILS

  The ceremony will take place on Saturday, December 13 in Pick-Staiger Concert Hall, 50 Arts Circle Drive.

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  TIME Saturday, December 13, 2025 at 4:00 PM - 6:00 PM

  LOCATION Pick-Staiger Concert Hall    map it

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  CONTACT Andi Joppie    andi.joppie@northwestern.edu EMAIL

  CALENDAR McCormick School of Engineering and Applied Science